#include <stdio.h>

int m,n,i,a,b,r,h;
long long x1,x2,y1,y2,x;
long long v[10001];

int main ()
{
    freopen ("oz.in","r",stdin);
    freopen ("oz.out","w",stdout);
    
    scanf ("%d %d",&n,&m);
    
    printf ("-1");
    
    return 0;
}